Method of and apparatus for making perforations in the wrappers of rod-shaped products

ABSTRACT

An method for increasing the permeability of tubular wrappers of a succession of cigarettes by at least one pulsed beam of coherent radiation issuing from a laser has a hollow drum-shaped conveyor cooperating with a rolling member to define an arcuate channel wherein successive cigarettes roll while advancing sideways past a perforating station. Each beam of coherent radiation is generated in or is caused to enter the interior of the conveyor prior to being influenced by one or more deflecting and/or focussing elements to be propagated substantially radially and through an opening of the hollow conveyor and to impinge upon the wrapper of a cigarette rolling at the perforating station.

CROSS-REFERENCE TO RELATED CASES

This application is a divisional application of application Ser. No.09/603,623, filed Jun. 26, 2000, now U.S. Pat. No. 6,532,966 and claimsthe priority of commonly owned German patent application Serial No. 19930 330.4, filed Jul. 2, 1999. The disclosure of the above-referencedGerman patent application, as well as that of each U.S. and foreignpatent and patent application mentioned in the specification of thepresent application, is incorporated herein by reference.

BACKGROUND OF THE INVENTION

The invention relates to improvements in apparatus for and in methods ofincreasing the permeability of wrapping material for rod-shapedproducts, especially rod-shaped smokers' products, and more particularlyto improvements in methods of and apparatus for perforating tubularenvelopes or wrappers of cigarettes or the like.

It is well known to enhance: the permeability of cigarette paper orother wrapping material for rod-shaped tobacco fillers and/or rod-shapedfilters for tobacco smoke prior as well as subsequent to the conversionof a running web of wrapping material into a tubular envelope formingpart of a continuous tobacco-containing rod; the leader of such rod isthereupon severed at regular intervals to yield a succession of discretecigarettes, cigars, cigarillos or other rod-shaped smokers' products. Itis equally known to enhance the permeability of selected portions oftubular envelopes forming part of discrete plain or filter cigarettes oranalogous rod-shaped smokers' products while the products rotate abouttheir own axes.

As a rule, a modem apparatus for enhancing the permeability of selectedportions of a running web or of selected portions of tubular wrappers ofsuccessive rod-shaped smokers' products (hereinafter called cigarettesfor short) comprises at least one source of high-energy radiation (suchas a laser beam) and means for directing the beam or beams into one ormore selected portions of the path for a running web of wrappingmaterial or of the path for successive plain or filter cigarettes. Ifthe apparatus is designed to perforate the finished (tubular) wrappersof plain or filter cigarettes, the cigarettes are caused to roll abouttheir own longitudinal axes while moving sideways past the perforatingstation. The purpose of the perforating treatment is to ensure that thepermeability of the tubular wrappers rises to a value at which anoptimum quantity of atmospheric air is caused to enter the column oftobacco smoke flowing from the lighted end of a cigarette toward themouth of the smoker. Cool atmospheric air is believed to exert abeneficial influence upon the nicotine and/or condensate contents oftobacco smoke.

U.S. Pat. No. 5,148,818 discloses a perforating apparatus which employsa source of coherent radiation (hereinafter called laser). The means forrolling successive cigarettes about their respective axes duringadvancement past the perforating station employs two coaxial drum-shapedconveyors and an endless flexible band. The path for the cigarettes isflanked by the band on the one hand, and by the conveyors on the otherhand. The speed of the belt departs from the peripheral speeds of theconveyors, and this causes the cigarettes to roll about their respectiveaxes. The laser is installed midway between the two rotary conveyors,and the beam of coherent radiation issuing from the laser is caused tocirculate while impinging upon a tubular wrapper at a selected frequencyto thus provide the wrapper with an array of perforations.

Published German patent application Serial No. 33 10 930 discloses aperforating apparatus wherein the peripheral surface of a rotarydrum-shaped conveyor transports a series of cigarettes sideways past astation where the wrappers of the cigarettes are acted upon by a laserbeam. The laser is confined in and is caused to move relative to acomplex heart-shaped reflector. Such apparatus are complex, bulky andunreliable.

Another perforating apparatus is disclosed in published German patentapplication Serial No. 34 31 051 which proposes a different combinationof a mobile laser and a directing system for the laser beam. Thedirecting system employs a complex array of mirrors and rotaryreflectors which are intended to focus a laser beam upon successivecigarettes while the cigarettes rotate about their respective axes andare simultaneously advanced sideways by a rotary conveyor toward, pastand beyond the perforating station.

Published German patent application Serial No. 34 31 067 discloses anapparatus which combines the features of the apparatus disclosed in theaforediscussed published German patent applications Serial Nos. 33 10930 and 34 31 051.

Published German patent application Serial No. 42 18 266 discloses aperforating apparatus wherein the cigarettes are transported and rolledby a set of drum shaped conveyors one of the conveyors carries apolygonal mirror which serves to direct a laser beam into the path forthe cigarettes.

A further perforating apparatus is disclosed in published German patentapplication Serial No. 27 51 522. This publication proposes to rollsuccessive cigarettes between the peripheral surface of a rotarydrum-shaped conveyor and the complementary concave surface of astationary rolling member. A laser beam trails successive cigarettesduring sidewise movement of the cigarettes in an arcuate rolling channelbetween the moving peripheral surface of the drum-shaped conveyor andthe stationary surface of the rolling member. The movement of the laserbeam is initiated and regulated by a rotary drum-shaped member having amirrored peripheral surface.

A drawback which is common to all of the above-enumerated perforating(permeability enhancing) apparatus is that the space requirements ofsuch apparatus are excessive, that the apparatus are complex and henceexpensive, as well as that their perforating action cannot be regulatedand maintained with a desired or required degree of accuracy andfacility.

Another drawback of certain conventional perforating apparatus is that,owing to their kinematics, the tubular wrapper of a cigarette can beperforated only during one-half of each revolution of a cigarette aboutits axis. Therefore, such apparatus are set up to expose the cigarettesto the action of laser beams which penetrate through the entirecigarette so that each beam provides perforations which are angularlyoffset by 180 degrees. Such solution is not entirely satisfactorybecause the energy requirements of the laser are very pronounced andalso because the dimensions of at least one of two simultaneously burnedperforations in the tubular wrapper of the cigarette are excessive.

OBJECTS OF THE INVENTION

An object of the invention is to provide an apparatus which is simple,compact and inexpensive and occupies space that is available but is notutilized in many machines or production lines for the making ofrod-shaped articles with gas-permeable tubular envelopes. Another objectof the invention is to provide an apparatus which is constructed andassembled in such a way that the beam or beams of coherent radiationneed not penetrate transversely across the entire rod-shaped commodity(such as a plain or filter cigarette) at the perforating station. Afurther object of the invention is to provide an apparatus which canform perforations while a rod-shaped article rotates through an angle of360° while advancing past the perforating station.

An additional object of the invention is to provide a novel and improvedmethod of manipulating high-energy beams of radiation in the course ofenhancing the penetrability of tubular wrappers for rod-shaped tobaccofillers and/or for rod-shaped filters for tobacco smoke.

Still another object of the invention is to provide a novellaser-conveyor combination which can be put to use in the above outlinedapparatus. A further object of the invention is to provide a novelconveyor which can be utilized with a source of high-energy radiation inthe apparatus of the present invention.

Another object of the invention is to provide the above outlinedapparatus with novel and improved means for rolling rod-shaped articlespreparatory to and during enhancement of permeability of their wrappers,such as wrappers made of cigarette paper, tipping paper or the like.

An additional object of the invention is to provide a cigarette makingmachine which embodies, or cooperates with, an apparatus exhibiting theabove outlined novel characteristics.

Still another object of the invention is to provide an apparatus whichoccupies space that is normally available in a machine or productionline for the making of plain and/or filter cigarettes or analogousrod-shaped commodities of the tobacco processing industry.

A further object of the invention is to provide an apparatus which candispense with mirrored rotary bodies forming part of numerous presentlyemployed apparatus for enhancing the permeability of tubular wrappers ofrod-shaped articles being turned out by the tobacco processing industry.

An additional object of the invention is to provide an apparatus whichexhibits the above outlined desirable novel characteristics and whichcan be designed to subject the wrappers of successive rod-shapedarticles of the tobacco processing industry to the action of a singlebeam of high-energy radiation or to simultaneous action of pluralhigh-energy radiation beams.

Another object of the invention is to provide rod-shaped smokers'products having tubular wrappers which were perforated in accordancewith the above outlined method and/or in the above outlined apparatus.

SUMMARY OF THE INVENTION

One feature of the instant invention resides in the provision of anapparatus for increasing or enhancing the permeabilities of tubularenvelopes or wrappers forming part of rod-shaped commodities and beingadapted to be perforated in response to exposure to high-energyradiation. The improved apparatus comprises means for rolling a seriesof successive rod-shaped commodities sideways along a predeterminedpath. The rolling means includes an at least partially hollow conveyorhaving an external surface bounding a portion of the aforementionedpath, and the apparatus further comprises a source of high-energyradiation and means for directing at least some of the radiation issuingfrom the source through the hollow conveyor and against the envelopes ofcommodities rolling along the aforementioned portion of thepredetermined path. The source can include at least: one pulsatinglaser, and the commodities can include or constitute rod-shaped smokers'products (such as plain or filter cigarettes, cigars or cigarillos). Theat least partially hollow conveyor can include a hollow rotary drumwhich is rotatable about a predetermined (e.g., horizontal) axis, andthe aforementioned external surface can constitute a cylindrical surfaceof the hollow drum. The rolling means of such apparatus can furthercomprise a rolling member (e.g., a stationary rolling member) having asecond surface cooperating with the peripheral surface of the hollowdrum to bound a channel which defines a portion of the predeterminedpath.

At least a portion of the radiation directing means is or can be located(installed) in the at least partially hollow conveyor. Such radiationdirecting means can include at least one mobile mirror, e.g., apivotable mirror.

The improved apparatus further comprises means for supplying the seriesof commodities into the predetermined path, preferably in such a waythat successive commodities of the series are maintained atpredetermined (particularly uniform) distances from each other. Therolling means can include means (such as the means for rotating thedrum-shaped conveyor) for moving the external surface at a speed whichis required to ensure that any point of the envelope of a commodityrolling along the aforementioned portion of the predetermined path,covers a distance greater than the circumferential length of a commoditywhile the supplying means advances each of the successive commoditiesthrough one of the predetermined distances. In such apparatus, theradiation directing means preferably includes at least one radiationreflecting element which is movable from a predetermined startingposition while directing high-energy radiation upon the envelope of acommodity rolling in the aforementioned portion of the predeterminedpath (within a predetermined interval of time) back to the startingposition. The speed of moving any point of an envelope of a commodityrolling along the aforementioned portion of the predetermined path ispreferably such that the interval during which the aforementioned pointcovers that part of the aforesaid distance which exceeds thecircumferential length of an envelope at least matches the predeterminedinterval of time to thus permit or enable the radiation reflectingelement to reassume its starting position while a commodity is on itsway into the aforementioned portion of the predetermined path.

The radiation directing means can comprise a mirror having a radiationreflecting surface, and such radiation directing means can furthercomprise means for pivoting the mirror about an axis which intersectsthe radiation reflecting surface of the mirror.

As already mentioned above, the at least partially hollow conveyor cancomprise a hollow rotary drum-shaped conveyor which is rotatable about apredetermined (such as horizontal) axis, and the means for directingradiation can comprise a mirror which is pivotable about a second axiswhich (a) is at, least substantially parallel to the predetermined axis,or (b) coincides with the predetermined axis. In the latter instance,the radiation directing means is or can be arranged to direct radiationupon the envelope of a commodity in the aforementioned portion of thepredetermined path at a distance from the predetermined axis which isless than the radius of the external surface of the hollow drum-shapedconveyor.

The radiation directing means can comprise at least one light refractingelement (e.g., a plano-convex lens). Such radiation directing means canfurther comprise a pivotable mirror; the at least one light refractingelement can be disposed between the radiation source and the pivotablemirror, or between the pivotable mirror and the locus of impigement ofhigh-energy radiation upon the envelope of a commodity in theaforementioned portion of the predetermined path.

As a rule, the radiation directing means of the improved apparatus willcomprise at least one of (a) a collector lens, (b) a diffractive opticalelement, and (c) a combination of a collector lens and a diffractiveoptical element.

If the at least partially hollow conveyor includes or is constituted bya hollow drum which is rotatable about a predetermined (e.g.,horizontal) axis and the aforementioned external surface is acylindrical external surface of the drum, the source can be locatedoutside of such at least partially hollow conveyor and can be set up todirect at least some of the high-energy radiation into the drum along asecond path which is at least substantially parallel to thepredetermined axis. The radiation directing means of such apparatus cancomprise a pivotable mirror which is arranged to direct radiation uponthe envelope of a commodity rolling along the aforementioned portion ofthe predetermined path, and means for deflecting radiation issuing fromthe source and for directing deflected radiation upon the pivotablemirror.

The at least partially hollow conveyor is provided with at least oneopening which is disposed in the external surface of such conveyor andis partially overlapped by a commodity rolling along the aforementionedportion of the predetermined path. The radiation directing means isarranged to direct radiation upon a commodity in the aforementionedportion of the predetermined path from the interior of the at leastpartially hollow conveyor and through the at least one opening. The atleast one opening can constitute an arcuate slot extending at leastsubstantially circumferentially of the cylindrical surface of the hollowdrum-shaped conveyor. The path for successive commodities can include orconstitute an arcuate channel having its center of curvature at leastclose to the axis of the cylindrical external surface of the drum-shapedconveyor. The latter can be provided with a plurality of arcuateopenings, and the radiation directing means can include means forsplitting a beam of coherent radiation issuing from the source into aplurality of discrete beams and means for directing each discrete beamthrough a different opening of the conveyor.

Another feature of the invention resides in the provision of a method ofperforating tubular envelopes of rod-shaped commodities by exposure tohigh-energy radiation. The method comprises the steps of rollingsuccessive commodities of a series of such commodities sideways along apredetermined path which partially surrounds a hollow conveyor,establishing a source of high-energy radiation (such as a laser whichemits a beam of coherent radiation), and directing from the source atleast one beam of high-energy radiation in the hollow conveyor (such asinto and/or within the hollow conveyor) and thence against the envelopesof successive commodities of the series rolling sideways along thepredetermined path.

The establishing step can include locating the source or sources ofhigh-energy radiation outside of the hollow conveyor.

The commodities can constitute rod-shaped smokers' products (such asplain or filter cigarettes, cigars or cigarillos) each of which has arod-like filler (e.g., of natural, reconstituted and/or artificialtobacco and/or filter material for tobacco smoke) confined in therespective envelope (e.g., an envelope consisting of or comprisingcigarette paper, tipping paper and/or other wrapping materialcustomarily employed in the tobacco processing industry).

The establishing step of the: improved method can comprise providing oremploying a laser, and the radiation directing step of such method cancomprise splitting the at least one beam into a plurality of (e.g., intotwo) discrete laser beams and directing the discrete laser beams upondifferent portions of envelopes of successive commodities of the serieswhile the commodities roll sideways along the predetermined path.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved perforating apparatus itself, however, both as to itsconstruction and the modes of assembling, installing and utilizing thesame, together with numerous additional important and advantageousfeatures and attributes thereof, will be best understood upon perusal ofthe following detailed description of certain presently preferredspecific embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic front elevational view of an apparatus whichembodies one form of the invention and is designed to form perforationsin selected portions of tubular envelopes of successive rod-shapedsmokers' products while the products roll sideways through an arcuatechannel between a hollow drum-shaped or cage-like rotary conveyor and astationary rolling member, with the radiation source omitted;

FIG. 2 is a fragmentary schematic plan view of a radiation source and ofa portion of the apparatus shown in FIG. 1, certain constituents of theillustrated structure being at least partially confined in the hollowconveyor;

FIG. 3 is a view similar to that of FIG. 1 but showing a portion of amodified apparatus; and FIG. 4 is a view similar to that of FIG. 2 butshowing certain parts of the apparatus embodying the structure of FIG.3.

DESCRIPTION OF PREFERRED EMBODIMENTS

The apparatus 1 of FIG. 1 can be installed in a cigarette maker or inanother machine or production line for the making of elongatedrod-:shaped commodities constituting smokers' products of the typewherein one or more tubular envelopes surround a rod-like filler offilter material for tobacco smoke and/or of comminuted natural,reconstituted and/or artificial tobacco. It is assumed that thecommodities are filter cigarettes of double unit length wherein a filtermouthpiece of double unit length is coaxial with and is located betweenand abuts the adjacent ends of two plain cigarettes of unit length. Eachplain cigarette: contains a rod-like tobacco filler and a tubularenvelope or wrapper of cigarette paper, and each filter mouthpiececontains a rod-like filler of filter material (e.g., acetate fibers) fortobacco smoke and a tubular envelope of cigarette paper or the like.Furthermore, each commodity comprises an adhesive-coated uniting bandwhich can be made of artificial cork or another suitable tipping paperand is convoluted around the entire filter mouthpiece of double unitlength as well as about the adjacent inner end portions of therespective plain cigarettes of unit length.

A machine which turns out filter cigarettes of double unit length isdisclosed, for example, in commonly owned U.S. Pat. No. 5,135,008granted Aug. 4, 1992 to Oesterling et al. for “METHOD OF AND APPARATUSFOR MAKING FILTER CIGARETTES”, and in commonly owned U.S. Pat. No.4,265,254 granted May 5, 1981 to Koch et al. for “APPARATUS FORPERFORATING CIGARETTE PAPER OR THE LIKE”. A machine for making plaincigarettes is disclosed, for example, in U.S. Pat. No. 4,281,670 grantedAug. 4, 1981 to Heitmann et al. for “APPARATUS FOR INCREASING THEPERMEABILITY OF WRAPPING MATERIAL FOR ROD-SHAPED SMOKERS' PRODUCTS”.

The apparatus 1 of FIG. 1 comprises an at least partially hollowdrum-shaped conveyor 16 which forms part of a means for rollingsuccessive commodities (hereinafter called cigarettes for short)sideways along an arcuate path one side of which is bounded by a portionof the cylindrical peripheral (external)—surface 14 of the conveyor 16.Such portion of the moving peripheral surface 14 and a concave surface18 of a stationary rolling member 17 define an arcuate channel 12 havinga width which at most matches the diameter of a cigarette 10 but ispreferably slightly less to thus ensure that successive cigarettes of aseries of equidistant cigarettes are caused to roll about theirrespective axes and to simultaneously move sideways in the directionindicated by arrows 22 while advancing through that portion of theirpath which extends through the channel 12.

The inlet of the channel 12 receives successive cigarettes 10 of theaforementioned series from a supplying means 2 here shown as adrum-shaped conveyor which is driven to rotate in a counterclockwisedirection (arrow 4). The peripheral surface of the supplying conveyor 2is provided with equidistant axially parallel ribs 8, and the front(leading) sides of the ribs 8 are provided with suction ports (notspecifically shown in FIG. 1) which attract cigarettes 10 duringtransport of cigarettes from a source (such as a conveyor whereon pairsof plain cigarettes of unit length are connected with filter mouthpiecesof double unit length by adhesive coated uniting bands, e.g., in amanner as described in the aforementioned U.S. Pat. No. '008 patent toOesterling et al.) to the inlet of the channel 12. The axis 6 of thesupplying conveyor 2 is but need not always be parallel to the axis ofthe hollow conveyor 16. The aforementioned suction ports at the frontsides of the ribs 8 are disconnected from a suction generating device(not shown) not later than at the inlet of the channel 12 to thus ensurepredictable entry of successive cigarettes 10 into the channel 12wherein the cigarettes roll about their respective longitudinal axes,and simultaneously advance sideways in the direction of arrows 22 at aspeed determined by the means (such as a driven shaft 16D) which servesto rotate the drum-shaped conveyor 16 about the axis 20.

The stationary rolling member 17 can be replaced with a mobile rollingmember which, defines the rolling surface 18 (e.g., by a portion of adriven belt), as long as the difference between the speeds of thesurfaces 14, 18 is such that successive cigarettes 10 of the seriessupplied by the conveyor 2 (or any other suitable cigarette supplyingmeans) suffices to ensure that each cigarette advancing in the channel12 completes a predetermined number of revolutions about its own axiswhile simultaneously covering a predetermined distance in the directionindicated by the arrows 22. Such combined rolling and sidewise movementis necessary to ensure a highly predictable change (increase) ofpermeability of the tubular envelope during advancement of a cigarette10 in a predetermined portion of its path in the channel 12, namelywhile the: envelope is being perforated by coherent high-energyradiation 34 supplied by a suitable source L, e.g., a laser shownschematically in FIG. 2. The just discussed difference between the(zero) speed of the concave rolling surface 18 and the speed of theconvex rolling surface 14 is selected in such a way that any given pointat the external surface of the envelope of a cigarette 10 rolling in thechannel 12 covers a distance exceeding the circumference of a cigarettewhile a cigarette on the supplying conveyor 2 covers a distance matchingthat between two neighboring ribs 8.

A cigarette 10 which leaves the channel 12 is attracted by suction ports(not shown) at the front side of the oncoming axially parallelperipheral rib 30 provided on a rotary drum-shaped take-off conveyor 24.

The latter is rotatable counterclockwise (see the arrow 28) about anaxis 26 which is parallel to the axes 6 and 20. It will be noted thatthe conveyors 2 and 24 rotate counterclockwise whereas the conveyor 16rotates clockwise. The conveyor 24 delivers successive (freshlyperforated) cigarettes 10 into the range of a severing tool whichdivides each such rod-shaped article into two filter cigarettes of unitlength. Reference should be had again to the aforementioned U.S. '008patent to Oesterling et al.

Referring to FIG. 2, the laser L is or can be located outside of or inthe interior of the hollow drum-shaped conveyor 16. The view of FIG. 2is taken in the direction of arrow 44 shown in FIG. 1 but with theconveyor 16 omitted. The pulsating beam of high-energy radiation issuingfrom the laser L is split and deflected by a mirror 32 forming part ofmeans for directing radiation upon the envelopes of successivecigarettes 10 rolling and advancing sideways in a predetermined portionof the channel 12. The beam 34 which is deflected by the mirror 32impinges upon a pivotable mirror 36. If the laser L is located outsideof the hollow conveyor 16, the beam issuing from the laser enters theinterior of the conveyor 16, preferably by advancing in parallelism withthe axis 20, to impinge upon the mirror 32 which, in turn, directs thebeam 34 against the pivotable mirror 36, namely at a 90° angle to theaxis 20. The mirror 36 deflects the oncoming beam 34 toward the internalsurface of the hollow conveyor 16, and more specifically into one of aplurality of arcuate slit- or slot-shaped openings 38 provided in thecylindrical body of the drum-shaped conveyor 16. A cigarette 10, theenvelope of which is being perforated, rolls relative to the surface 14along an opening 38 so that the rolling cigarette is in contact with thesurface 14 practically all the way from end to end save for the narrowgap caused by the provision of the opening 38 which is necessary inorder to enable the pulsating beam 34 of high-energy radiation toimpinge upon and to perforate predetermined portions of the envelope.

As already mentioned above, a cigarette 10 which advances in thedirection of arrows 22 while rolling about its own axis on the way fromthe inlet to the outlet of the channel 12 completes more than one fullrevolution, i.e., more than is necessary to provide its envelope with acircumferentially complete array of perforations. This renders itpossible to pivot the mirror 36 back to a starting angular position inwhich the mirror is ready to direct the beam 34 upon the envelope of thenext-following cigarette 10 which has entered the channel 12. This novelfeature renders it possible that the permeability of the envelopes ofeach of a short or long series of successive cigarettes 10 supplied bythe conveyor 2 is increased to the same extent.

FIGS. 1 and 2 further show a plano-convex lens 40 which is installed inthe path of the beam 34 from the pivotable mirror 36 to one of theslot-shaped openings 38 in the hollow conveyor 16. The purpose of thelens 40 is to focus the beam 34 in such a way that the focal point ofthe laser beam 34 is located exactly at the locus 42 of impingement ofthe beam 34 upon the envelope of the cigarette 10 in the rolling channel12.

The pivotable mirror 36 causes the beam 34 to follow a rolling cigarette10 on its way from the inlet toward the outlet of the channel 12. Thisensures that the envelope of such cigarette is provided with acircumferentially complete array of perforations formed by the pulsatingbeam 34. The exact loci of perforations are determined by the axialposition of a cigarette 10 rolling in the channel 12 relative to thatarcuate slot 38 which permits the beam 34 to propagate itself from thepivoting mirror 36, through the focussing lens 40, and into the rollingchannel 12.

FIG. 2 shows a driving unit 46 which serves as a means for pivoting themirror 36 relative to the mirror 32 and lens 40 about an axis 46A inorder to direct the beam 34 upon the envelope of the cigarette 10 in therolling channel 12. FIG. 2 further shows that the mirror 32 is partlyreflecting so that a portion (34′) of the beam issuing from the laser Lcan penetrate through the mirror 32 to impinge upon the fully reflectingmirror 32′. The latter deflects the beam 34′ upon a second pivotablemirror 36′ which, in turn, directs the beam 34′ against a secondplano-convex; focussing lens 40′ serving to direct this beam upon aselected (second) portion of the envelope of a, cigarette 10 rolling inthe channel 12. Thus, the apparatus 1 including the structure of FIGS. 1and 2 can simultaneously provide a tubular envelope with two axiallyspaced-apart arrays of perforations, e.g., one array for each of the twoultimate products (filter cigarettes of unit length). The mirror 36′ ispivotable by a second driving unit 46′ which is, or which can be,identical with the driving unit 46 for the mirror 36. Driving units (46,46′) which can be utilized to pivot mirrors serving to reflect discretelaser beams are well known in the relevant arts.

The arrangement can be such that the deflecting mirror 32 directs 50% ofradiation issuing from the laser L toward the pivotable mirror 36 andpermits the remaining 50% of radiation (namely the beam 34′) to impingeupon and to be fully reflected by the mirror 32′.

FIGS. 3 and 4 show certain relevant details of a second permeabilityenhancing apparatus 1′. All such parts of the apparatus 1′ which areidentical with or clearly analogous to the corresponding parts of theapparatus 1 of FIGS. 1 and 2 are denoted by similar referencecharacters. The only significant difference between the apparatus 1 and1′ is that, in the apparatus 1′, the plano-convex lenses 40, 40′ arereplaced with similar lenses 48, 48′ which are respectively locatedbetween the mirrors 32, 32′ on the one hand, and the pivotable mirrors36, 36′ on the other hand. Thus, the lenses 48, 48′ respectively focusthe laser beams 34, 34′ upon the pivotable mirrors 36, 36′ before thesemirrors direct the focussed beams 34, 34′ upon selected portions of theenvelope of a cigarette 10 rolling along the external surface 14 of thehollow conveyor 16 and over the respective slot- or slit-shaped openings38.

It goes without saying that each of the apparatus 1 and 1′ can operateonly with one mirror (32 or 32′), with one mirror (36 or 36′) and withone lens (such as 40 or 48).

An important advantage of the improved method and apparatus is that theyare simpler and the apparatus 1, 1′ are more compact than heretoforeknown permeability enhancing methods and apparatus. Thus, the variousmirrors and lenses can be accommodated in a space (in the interior ofthe conveyor 16) which is available but not utilized in conventionalperforating apparatus. Moreover, the paths for the beams of coherenthigh-energy radiation are shorter and can thus be controlled with ahigher degree of accuracy. Still further, the various mirrors and lensesare simpler and less expensive than those which must be employed inconventional apparatus. For example, it is possible to dispense withcomplex and expensive mirrored drums.

The mirrors 36 and 36′ are preferably mounted in such a way that theirpivot axes intersect the respective radiation reflecting surfaces. FIGS.1 and 3 show that the mirrors 36 are pivotable about axes which areparallel to the axis 20 of the hollow conveyor 16. However, it isequally possible and within the purview of the invention to mount themirrors 36 (as well as the mirrors 36′) in such a way that their pivotaxes coincide with the axis 20, i.e., that the length of that portion ofa beam 34 or 34′ which propagates itself from the mirror 36 or 36′ tothe tubular envelope of a cigarette 10 in the rolling channel 12 matchesor closely approximates the radius of the external surface 14. Also,such design ensures that the length of the beam portion between themirror 36 or 36′ and the envelope of a cigarette 10 in the rollingchannel. 12 remains unchanged during each and every stage of enhancementof permeability of such envelope.

An advantage of the embodiments which are actually shown in FIGS. 1 and3, namely of the embodiments wherein the pivot axes for the mirrors 36and 36′ are nearer to the rolling channel 12 than the axis 20 of thehollow conveyor 16 (i.e., wherein the radius of the surface 14 isgreater than the distance from the reflecting surface of the mirror 36or 36′ to the envelope of a cigarette 10 in the channel 12) is that thelens 40 or 40′, or the lens 48 or 48′, renders it possible to focus thebeam (34 or 34′) impinging upon the envelope of a cigarette 10 withinthe conveyor 16 with a degree of accuracy such that one can provide theenvelope with perforations having diameters in the desirable range of0.1 mm or thereabout. In contrast to the just described operation of theillustrated apparatus 1 and 1′, conventional apparatus must employcomplex optical elements which are called upon to reduce the diametersof laser beams from a diameter in the range of between about 5 and 11 mmto a diameter which is needed to make perforations with diameters(maximum dimensions) in the range of 0.1 mm.

In most or in many instances, the optical elements 40, 40′ or 48, 48′constitute collector lenses or diffractive optical elements orcombinations of collector lenses and diffractive optical elements. Anadvantage of the embodiment (apparatus 1) which is shown in FIGS. 1 and2 is that relatively small lenses 40, 40′ suffice to focus therespective beams 34, 34′ upon the envelopes of cigarettes 10 in thechannel 12. This renders it possible to readily accommodate the lenses40, 40′ in the interior of the conveyor 16.

It is also within the purview of the present invention to install themirrors 36′ and/or 36, 36′ in the conveyor 16 in such a way that theradius of the surface 14 is smaller than the distance of mirror(s) 36and/or 36, 36′ from the locus (42) of impingement of a laser beam 34 or34′ upon the envelope of a cigarette 10 in the rolling channel. All thatis necessary is to select appropriate mirrors and/or lenses which renderit possible to adequately focus the laser beam or beams upon thesurfaces of the cigarettes 10 in the channel 12 in order to makeperforations having the desired diameters.

As already mentioned hereinbefore, it is desirable and advantageous toselect the ratio of distances between the ribs 8 on the supplyingconveyor 2 to the distance covered by any point on the envelope of acigarette 10 in the channel 12 in such a way that the distance coveredby such point exceeds the circumferential length of an envelope before anext-following cigarette enters that portion of the channel 12 whereinit begins to be acted upon by a beam 34′ and/or 34. This enables themirror 36′ and/or 36 to reassume its starting angular position (inresponse to pivoting by the drive 46′ and/or 46) in good time to proceedwith the next perforating step. All that is necessary is to properlyrelate the speeds of the conveyors 2, 16 to each other and to the speedof pivoting the mirror 36′ and/or 36 (by the drive 46′ and/or 46) backto the starting position(s) of the mirror 36′ and/or 36; thisestablishes an interval of time which follows the making of acircumferentially complete array or set of perforations and is longenough to enable the mirror 36′ and/or 36 to thereupon reassume itsstarting position.

The above considerations apply independently of the distances betweensuccessive cigarettes 10 in the rolling channel 12. For example, if theangular spacing of ribs 8 on the conveyor 2 equals 12π, the spacingbetween successive cigarettes 10 in the channel 12 can also equal 12π orit can slightly exceed or be slightly smaller than 12π. This feature isbelieved to constitute a patentable innovation in combination with orindependently of the feature of installing one or more radiationdirecting elements (such as L, 32, 32′ 36, 36′, 40, 40′, 48, 48′) in theinterior of the rolling conveyor 16.

The just discussed feature of the invention can be resorted toirrespective of whether the lens or lenses (40, 40′) is or are installedbetween the mirror(s) 36 or 36′ and the channel 12 (see FIGS. 1 and 2)or between the mirror (s) 32 or 32′ and the mirror or mirrors 36 or 36′(see FIGS. 3 and 4). All that is necessary is to properly select thecharacteristics of the lenses 40, 40′, 48 and/or 48′.

In each of the aforediscussed embodiments, it is possible to provide thecollector lenses with surface coatings to thus obtain so-calleddiffractive optics. For example, the coatings can be of a nature suchthat a laser beam having a circular cross-sectional area is convertedinto a beam having a polygonal cross-sectional area; this is advisablewhen the envelopes of the cigarettes 10 or analogous rod-shaped productsare to be provided with non-circular perforations.

Still further, and as shown in FIGS. 2 and 4, the components 32 of theradiation directing means can constitute diffractive optics capable ofsplitting an incoming beam of high-energy radiation into a plurality ofdiscrete beams. Diffractive optics are particularly desirable when it isnecessary to enhance the focussing of a laser beam. Thus, even if theimproved apparatus employs a relatively weak collector lens, and if thediameter of the round cross-sectional area of a laser beam is relativelylarge (e.g., in excess of 7 mm), the apparatus can make relatively smallperforations with diameters below 0.1 mm. Still further, each embodimentof the present invention is preferably (or can be) designed to achieveas pronounced depth of field of the optically imaged laser beam aspossible. The reason is that this renders it possible to disregard thosevariations of distances between the pivotable mirror 36 and/or 36′ andthe locus or loci of impingement of the beam(s) upon a rolling envelopewhich are attributable to the fact that the pivot axis of the pivotablemirror does not coincide with the axis 20 of the hollow conveyor 16.

It is often preferred to install the laser L (or another suitable sourceof high-energy radiation) outside of the conveyor 16, i.e., to utilizethis hollow or partially hollow conveyor as a housing for variouscomponents of the radiation directing means but not for the radiationsource. An advantage of such apparatus is that the laser L or anequivalent or analogous source of high-energy radiation is readily ormore readily accessible at all times. Without further analysis, theforegoing will so fully reveal the gist of the present invention thatothers can, by applying current knowledge, readily adapt it for variousapplications without omitting features that, from the standpoint ofprior art, fairly constitute essential characteristics of the genericand specific aspects of the aforedescribed contribution to the art ofperforating cigarette paper or the like and, therefore, such adaptationsshould and are intended to be comprehended within the meaning and rangeof equivalence of the appended claims.

1. A method of perforating tubular envelopes of rod-shaped commodities by exposure to high-energy radiation, comprising the steps of: rolling successive commodities of a series of commodities sideways along a predetermined path partially surrounding a hollow conveyor; establishing a source of high-energy radiation at the hollow conveyor; and directing from the source at least one beam of high-energy radiation in the hollow conveyor and thence against the envelopes of successive commodities of said series rolling sideways along said predetermined path, wherein said establishing step includes locating the source of high-energy radiation outside of the hollow conveyor.
 2. The method of claim 1, wherein said establishing step includes providing a laser and said directing step includes splitting the at least one beam into a plurality of discrete laser beams and directing said discrete laser beams upon different portions of envelopes of successive commodities of said series while the commodities roll sideways along said predetermined path.
 3. The method of claim 1, wherein the commodities are rod shaped smokers' products each having a rod-like filler confined in the respective envelope.
 4. A method of perforating tubular envelopes of rod-shaped commodities by exposure to high-energy radiation, comprising the steps of: rolling successive commodities of a series of commodities sideways along a predetermined path; supplying said series of commodities into said path while maintaining successive commodities of said series at predetermined distances from each other, said rolling step including rolling the commodities at a speed such that any point of the envelope of a commodity rolling along a predetermined portion of said path covers a distance greater than the circumferential length of a commodity during advancement of each of said successive commodities through one of said predetermined distances; establishing a source of high-energy radiation; and directing from the source at least one beam of high-energy radiation against the envelopes of successive commodities of said series rolling sideways along said predetermined portion of said path.
 5. The method of claim 4, wherein said directing step includes moving at least one radiation reflecting element from a predetermined starting position while directing radiation upon the envelope of a commodity in said predetermined portion of said, path and within a predetermined interval of time back to said starting position, said speed of moving any point of an envelope of a commodity rolling along said predetermined portion of said path being such that the interval during which said point covers the part of said distance exceeding said circumferential length at least matches said predetermined interval of time to thus enable the radiation reflecting element to reassume its starting position while a commodity is on its way into said predetermined portion of said path. 